Prior to the present awareness of the hazardous nature of numerous waste materials, these materials were typically either dumped or were allowed to enter the ecosystem in other ways. Examples of such practices were the widespread dumping of wastes containing chlorinated hydrocarbons onto land or the release of toxic heavy metals, such as those produced in metal plating or metal finishing industries, into sewerage systems and hence to the sludges produced from sewage treatment or land farming. Such materials can and have entered the human food chain either through leaching by rain of the hazardous material into the underground water table or from food grown on land that has been contaminated by these substances.
Numerous attempts have been made to address such environmental problems. In the past, heavily contaminated soil or sludge was often transported to a site remote from population centers or from sources of drinking water. The contaminated soil or sludge was then deposited into "safe" landfills after fixation.
An attractive technical approach to the problem of disposing of hazardous waste material is offered by incineration which facilitates the conversion of chlorinated hydrocarbons into less hazardous by-products such as carbon dioxide and hydrogen chloride, or heavy metals into environmentally safe oxides. For this method to be successful, however, two requirements must be met. First, the incineration must be complete since partial oxidation of chlorinated hydrocarbons may result in the production of compounds that are more harmful than the original material. These harmful compounds may be either in the form of exhaust gases or residual ashes, or both. Second, all harmful combustion products must be removed completely from the gas stream produced by the incineration and thereafter rendered harmless.
Thus far, incineration processes have not met these two essential requirements. One problem is presented by the complexity and sensitivity of the control system required for effecting a complete combustion. Another obstacle has been the size and cost of incinerators capable of eliminating industrial quantities of waste. The size and cost of adequate scrubbing systems for cleaning the resulting gases are similarly daunting. Moreover, the cost efficiency of existing incineration systems is significantly reduced by the need for mechanical stirring or vibration within the scrubbing systems. Another formidable limitation is the opposition by the public toward both the location of such an incinerator in their vicinity and the transportation of hazardous wastes thereto.
As a result, incineration plants have generally been very large, costly, and, by necessity, stationary. Consequently, large quantities of hazardous waste materials have had to be carted from the waste-producing location over long distances on public roads with an obvious concomitant risk to the environment. In addition, the resistance by neighborhoods to the siting of such incinerating plants in their localities has grown to such a level as to inhibit the construction and use of this possibly beneficial technology.
It is accordingly an object of this invention to provide a process for the complete incineration of hazardous waste into environmentally safe exhaust gases and residual ash.
It is another object of this invention to provide such a process wherein all harmful combustion by-products are removed from the gas stream produced by the incineration process and thereafter rendered harmless.
It is another object of this invention to provide such a process wherein harmful particulate matter is removed from the gas stream by passing the gas stream through a scrubber chamber without the need for mechanical vibration or stirring.
It is another object of this invention to provide an industrial scale incinerator system which is mobile or transportable to a desired location.
Still another object of this invention is to provide an incineration system which permits hazardous wastes to be treated at the site of their production, thus eliminating the need for costly and dangerous transportation of such materials.